Treatment of patients with myocardial infarction who present with a paced rhythm.

BACKGROUND: A paced rhythm can mask the electrocardiographic features of an acute myocardial infarction, complicating timely recognition and treatment. OBJECTIVE: To evaluate characteristics, treatment, and outcomes among patients presenting with paced rhythms during myocardial infarction. DESIGN: Retrospective cohort study. SETTING: U.S. acute care hospitals. PATIENTS: 102 249 Medicare beneficiaries at least 65 years of age who were treated for acute myocardial infarction between 1994 and 1996. MEASUREMENTS: Provision of three treatments for acute myocardial infarction (emergent reperfusion, aspirin, and beta-blockers), death at 30 days, and long-term follow-up. RESULTS: 1954 patients (1.9%) presented with paced rhythms during myocardial infarction. These patients were older; were predominantly male; and had higher rates of congestive heart failure, diabetes, and previous infarction. They were significantly less likely to receive emergent reperfusion (relative risk [RR], 0.27 [95% CI, 0.22 to 0.33]), aspirin (RR at admission, 0.91 [CI, 0.88 to 0.94]; RR at discharge, 0.87 [CI, 0.83 to 0.92]), and beta-blockers at admission (RR, 0.89 [CI, 0.82 to 0.96]). In addition, there was a trend toward decreased use of beta-blockers at discharge (RR, 0.91 [CI, 0.76 to 1.06]). Crude mortality rates were higher among patients with paced rhythms than among those without at 30 days (25.8% vs. 21.3%; P = 0.001) and at 1 year (47.1% vs. 36.1%; P = 0.001). Among patients with paced rhythms, risk for death at 30 days decreased after adjustment for illness severity and decreased use of therapy (RR, 1.03 [CI, 0.93 to 1.14]). Patients with paced rhythms remained at additional risk for long-term mortality (hazard ratio, 1.12 [CI, 1.06 to 1.18]). CONCLUSIONS: Patients with paced rhythms were less likely than those without to receive treatment for acute myocardial infarction and had poorer short- and long-term outcomes. However, this mortality risk diminished after adjustment for treatment. This suggests that improved recognition and treatment of myocardial infarction may improve outcomes, particularly in the short term.

Duke Scholars

Author Kevin Phillip Weinfurt Population Health Sciences